Photographed by George A. Doeright in 1935.
OK, I can see this is the "missing link" between the E6 and K4.
Well, design-wise, the E.6 was more advanced than the K.2 and in level territory could out perform the K.2. They paid a lot of attention to boiler and firebox design to produce a better steaming engine.
Any idea of a K-2 would have been either a "light" or "heavy" pacific?